The owner of an average house in the Pennridge School District will pay about $48 more in property tax next year under a $21.8-million district budget unveiled yesterday.

The tax under the 1986-87 budget proposal is up 8 mills, to 114 mills, with earnings expected to rise a little more than $1 million to $9.9 million. It would be the district's 12th consecutive property tax increase.

Calculated on what district Business Manager Donald B. Stubbs said is an average real estate assessment of $6,000, a homeowner's property tax bill would rise to $684 from $636.

The occupation tax under the budget proposal would remain at 575 mills.

The School Board is expected to adopt a tentative budget at its meeting at 8 p.m. Monday in the district Education Center. Adoption of a final budget is scheduled for May 19.

Board members and district administrators, speaking at a news conference held to present the budget, attributed the property tax increase largely to a 17.6-mill rise next year in the cost of teachers' salaries and benefits. But they also said that it is needed to maintainwhat they said are the district's high educational standards.

District teachers are in the first year of a three-year contract that will see their salaries increase a net 9.8 percent next year, with the average salary rising to $30,789 from $28,152 this year.

In addition, Pennridge plans to hire five new elementary school teachers next year at a cost of $130,000, including salaries and benefits. The teachers are needed because of growing enrollment in the lower grades, district officials said.

Like last year, when the board raised the property tax 9 mills and the occupation tax 50 mills, board members and administrators said the tax increase is needed primarily to maintain the district's quality of education.

Superintendent John E. Slattery said district students "achieve very, very well" on standardized tests, routinely scoring a year above their grade levels. "The board is very pleased with the results and wants to maintain that level of achievement," he said.

Slattery said students' achievements should also blunt any community opposition to the tax increase. "Given our track record of standardized achievement, I would expect the community to be supportive of the board in this budget," he said.

The almost 10 percent rise in teaching costs is offset in part by increases in the district's state subsidy and taxes other than the real estate tax.

The district subsidy in Gov. Dick Thornburgh's budget is $245,689, or almost 3 mills higher than this year, although district officials cautioned that the amount is tentative.

Tax revenues projections show the occupational privilege yielding $10,000 more next year; wage and income taxes, an added $125,977; occupation taxes, $166,190 more, and real estate transfer taxes, an extra $100,000. Collection of delinquent real estate taxes is expected to rise $45,000, to $275,000 from $230,000.

Other highlights of the budget are:

- The contribution to the athletic fund would rise to $33,000 from $20,000 because gate receipts at athletic events are expected to decrease because the district is switching from the Bux-Mont to the Suburban 1 league.

- The payment to the Upper Bucks Vo-Tech School would rise 7 percent, to $951,000 from $888,800. The district sends about 330 students to the school, Slattery said.

- The cost of nursing services would rise $33,000 because the district plans to hire an undetermined number of part-time nurses or emergency medical technicians to supplement its two full-time and six part-time nurses. The added employees are need to provide daily emergency care in all schools, Slattery said.

- The cost of property liability insurance is expected to rise at least $48,040, to $130,850 from $82,810.

- Fifteen thousand dollars has been budgeted to correct hazards found by a study of art materials and equipment in district schools. Included in the work could be providing proper ventilation for the ceramic kilns.